Planarized extreme ultraviolet lithography blank with absorber and manufacturing system therefor

ABSTRACT

An extreme ultraviolet (EUV) mask blank production system includes: a substrate handling vacuum chamber for creating a vacuum; a substrate handling platform, in the vacuum, for transporting an ultra-low expansion substrate loaded in the substrate handling vacuum chamber; and multiple sub-chambers, accessed by the substrate handling platform, for forming an EUV mask blank includes: a first sub-chamber for forming a multi-layer stack, above the ultra-low expansion substrate, for reflecting an extreme ultraviolet (EUV) light; and a second sub-chamber for forming a bi-layer absorber, formed above the multi-layer stack, for absorbing the EUV light at a wavelength of 13.5 nm provides a reflectivity of less than 1.9%.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/023,507 filed Jul. 11, 2014, and the subjectmatter thereof is incorporated herein by reference thereto.

The present application contains subject matter related to aconcurrently filed U.S. Patent Application by Vinayak Vishwanath Hassan,Majeed A. Foad, Cara Beasley, and Ralf Hofmann, entitled “EXTREMEULTRAVIOLET MASK BLANK PRODUCTION SYSTEM WITH THIN ABSORBER ANDMANUFACTURING SYSTEM THEREFOR”. The related application is assigned toApplied Materials, Inc. and is identified by docket number021475USA/ATG/ATG/ESONG. The subject matter thereof is incorporatedherein by reference thereto.

TECHNICAL FIELD

The present invention relates generally to extreme ultravioletlithography blanks, and manufacturing and lithography systems for suchextreme ultraviolet lithography blanks.

BACKGROUND

Extreme ultraviolet lithography (EUV, also known as soft x-rayprojection lithography) is a contender to replace deep ultravioletlithography for the manufacture of 0.0135 micron, and smaller, minimumfeature size semiconductor devices.

However, extreme ultraviolet light, which is generally in the 5 to 100nanometer wavelength range, is strongly absorbed in virtually allmaterials. For that reason, extreme ultraviolet systems work byreflection rather than by transmission of light. Through the use of aseries of mirrors, or lens elements, and a reflective element, or maskblank, coated with a non-reflective absorber mask pattern, the patternedactinic light is reflected onto a resist-coated semiconductor substrate.

The lens elements and mask blanks of extreme ultraviolet lithographysystems are coated with reflective multilayer coatings of materials suchas molybdenum and silicon. Reflection values of approximately 65% perlens element, or mask blank, have been obtained by using substrates thatare coated with multilayer coatings that strongly reflect light withinan extremely narrow ultraviolet bandpass; e.g., 12.5 to 14.5 nanometerbandpass for 13.5 nanometer extreme ultraviolet (EUV) light.

There are various classes of defects in semiconductor processingtechnology which cause problems. Opaque defects are typically caused byparticles on top of the multilayer coatings or mask pattern which absorblight when it should be reflected. Clear defects are typically caused bypinholes in the mask pattern on top of the multilayer coatings throughwhich light is reflected when it should be absorbed. And phase defectsare typically caused by scratches and surface variations beneath themultilayer coatings which cause transitions in the phase of thereflected light. These phase transitions result in light waveinterference effects which distort or alter the pattern that is to beexposed in the resist on the surface of the semiconductor substrate.Because of the shorter wavelengths of radiation which must be used forsub-0.0135 micron minimum feature size, scratches and surface variationswhich were insignificant before now become intolerable.

The problem that the thin absorber addresses is the shadowing issuesseen with thicker absorbers as the pattern gets smaller, which ends uplimiting the size features that can be printed on a substrate. Achievinga thinner absorber requires using new materials that absorb 13.5 nmlight better than the current absorbers in use.

In view of the need for the increasingly smaller feature size ofelectronic components, it is increasingly critical that answers be foundto these problems. In view of the ever-increasing commercial competitivepressures, along with growing consumer expectations, it is critical thatanswers be found for these problems. Additionally, the need to reducecosts, improve efficiencies and performance, and meet competitivepressures adds an even greater urgency to the critical necessity forfinding answers to these problems.

Solutions to these problems have been long sought but prior developmentshave not taught or suggested any solutions and, thus, solutions to theseproblems have long eluded those skilled in the art.

SUMMARY

An embodiment of the present invention is an extreme ultraviolet (EUV)mask blank production system including: a substrate handling vacuumchamber for creating a vacuum; a substrate handling platform, in thevacuum, for transporting an ultra-low expansion substrate loaded in thesubstrate handling vacuum chamber; and multiple sub-chambers, accessedby the substrate handling platform, for forming an EUV mask blankincluding: a first sub-chamber for forming a multi-layer stack, abovethe ultra-low expansion substrate, for reflecting an extreme ultraviolet(EUV) light; and a second sub-chamber for forming a bi-layer absorber,formed above the multi-layer stack, for absorbing the EUV light at awavelength of 13.5 nm provides a reflectivity of less than 1.9%.

An embodiment of the present invention is an extreme ultraviolet (EUV)mask blank system including: an ultra-low expansion substrate includessurface imperfections; a planarization layer on the ultra-low expansionsubstrate for encapsulating the surface imperfections; a multi-layerstack over the planarization layer; and a bi-layer absorber over themulti-layer stack includes determining a percent of reflectivity bycontrolling a thickness of a primary absorber layer and a secondaryabsorber layer of the bi-layer absorber deposited to a combinedthickness of 30 nm provides a reflectivity of less than 1.9%.

Certain embodiments of the invention have other steps or elements inaddition to or in place of those mentioned above. The steps or elementwill become apparent to those skilled in the art from a reading of thefollowing detailed description when taken with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an extreme ultraviolet (EUV) mask blank production system.

FIG. 2 is a cross-sectional view of an EUV mask blank in accordance withan embodiment.

FIG. 3 is an orthogonal view of an EUV mask.

FIG. 4 is a flow chart of a method for making the EUV mask blank withultra-low defects.

FIG. 5 is a flow chart of an alternative method for making the EUV maskblank with ultra-low defects.

FIG. 6 is an optical train for an EUV lithography system.

FIG. 7 shows a plot of a reflectivity percentage as a function of athickness of the primary absorber layer of FIG. 2.

DETAILED DESCRIPTION

The following embodiments are described in sufficient detail to enablethose skilled in the art to make and use the invention. It is to beunderstood that other embodiments would be evident based on the presentdisclosure, and that system, process, or mechanical changes may be madewithout departing from the scope of the present invention.

In the following description, numerous specific details are given toprovide a thorough understanding of the invention. However, it will beapparent that the invention may be practiced without these specificdetails. In order to avoid obscuring the present invention, somewell-known circuits, system configurations, and process steps are notdisclosed in detail.

The drawings showing embodiments of the system are semi-diagrammatic andnot to scale and, particularly, some of the dimensions are for theclarity of presentation and are shown exaggerated in the drawing FIGs.Similarly, although the views in the drawings for ease of descriptiongenerally show similar orientations, this depiction in the FIGs. isarbitrary for the most part. Generally, the invention can be operated inany orientation.

Where multiple embodiments are disclosed and described having somefeatures in common, for clarity and ease of illustration, description,and comprehension thereof, similar and like features will be describedwith similar reference numerals.

For expository purposes, the term “horizontal” as used herein is definedas a plane parallel to the plane or surface of a mask blank, regardlessof its orientation. The term “vertical” refers to a directionperpendicular to the horizontal as just defined. Terms, such as “above”,“below”, “bottom”, “top”, “side” (as in “sidewall”), “higher”, “lower”,“upper”, “over”, and “under”, are defined with respect to the horizontalplane, as shown in the figures. The term “on” indicates that there isdirect contact between elements.

The term “processing” as used herein includes deposition of material orphotoresist, patterning, exposure, development, etching, cleaning,and/or removal of the material or photoresist as required in forming adescribed structure.

Referring now to FIG. 1, therein is shown an extreme ultraviolet (EUV)mask blank production system 100. The integrated EUV mask blankproduction system 100 includes a mask blank loading and carrier handlingsystem 102 having load ports 104 into which transport boxes containingsubstrates 105, such as substrates of glass, silicon, or other ultra-lowthermal expansion material, are loaded. An airlock 106 provides accessto a substrate handling vacuum chamber 108. In an embodiment, thesubstrate handling vacuum chamber 108 can contain two vacuum chambers, afirst vacuum chamber 110 and a second vacuum chamber 112. The firstvacuum chamber 110 can contain an initial substrate handling platform114 and the second vacuum chamber 112 can contain a second substratehandling platform 116.

The substrate handling vacuum chamber 108 can have a plurality of portsaround its periphery for attachment of various subsystems. The firstvacuum chamber 110 can, for example, have a degas subsystem 118, a firstphysical vapor deposition sub-chamber 120 such as a bi-layer absorberdeposition chamber, a second physical vapor deposition sub-chamber 122such as a backside chucking layer deposition chamber, and a precleansubsystem 124.

The second vacuum chamber 112 can have a first multi-cathode sub-chamber126 such as a multilayer deposition chamber, a flowable chemical vapordeposition (FCVD) sub-chamber 128 such as a planarization layerdeposition chamber, a cure sub-chamber 130, and a second multi-cathodesub-chamber 132 connected to it.

The initial substrate handling platform 114 is capable of moving anultra-low expansion substrate, such as a first in-process substrate 134,among the airlock 106 and the various subsystems around the periphery ofthe first vacuum chamber 110 and through slit valves, not shown, in acontinuous vacuum. The second substrate handling platform 116 can movean ultra-low expansion substrate, such as a second in-process substrate136, around the second vacuum chamber 112 while maintaining the secondin-process substrate 136 in a continuous vacuum.

It has been discovered that the integrated EUV mask blank productionsystem 100 can provide an environment for manufacturing EUV mask blanks,while minimizing the manual transport of the first in-process substrate134 and the second in-process substrate 136.

Referring now to FIG. 2, therein is a cross-sectional view of an EUVmask blank 200 in accordance with an embodiment. The EUV mask blank 200can have an ultra-low thermal expansion substrate 202 of glass, silicon,or other ultra-low thermal expansion material. The ultra-low thermalexpansion materials include fused silica, fused quartz, calciumfluoride, silicon carbide, silicon oxide-titanium oxide, or othermaterial having a thermal coefficient of expansion within the range ofthese materials.

It has been discovered that a planarization layer 204 can be used forfilling surface imperfections 203, such as pits and/or defects in theultra-low expansion substrate 202, covering particles on top of theultra-low expansion substrate 202, or smoothing an already planarizedsurface of the ultra-low expansion substrate 202 to form a planarsurface 205.

A multi-layer stack 206 can be formed on the planarization layer 204 toform a Bragg reflector. Due to the absorptive nature of the illuminatingwavelengths used in EUV lithography, reflective optics are used. Themulti-layer stack 206 may be made of alternating layers of high-Z andlow-Z materials, such as molybdenum and silicon in order to form areflector.

A capping layer 208 is formed on the multi-layer stack 206 opposite theultra-low expansion substrate 202 for forming a capped Bragg reflector.The capping layer 208 can be a material such as Ruthenium (Ru) or anon-oxidized compound thereof to help protect the multi-layer stack 206from oxidation and any chemical etchants to which the EUV mask blank 200may be exposed during subsequent mask processing. Other material such astitanium nitride, boron carbide, silicon nitride, ruthenium oxide, andsilicon carbide may also be used in the capping layer 208.

A bi-layer absorber 210 is placed on the capping layer 208. The bi-layerabsorber 210 can include a primary absorber layer 212 and a secondaryabsorber layer 214. The bi-layer absorber 210 is of a material pairhaving a high absorption coefficient in combination for a particularfrequency of EUV light (about 13.5 nm). In an embodiment, the primaryabsorber layer 212, such as silver (Ag), can be formed directly on thecapping layer 208 and the secondary absorber layer 214, such as nickel(Ni), can be formed directly on the primary absorber layer 212.

The bi-layer absorber 210 must be kept as thin as possible in order toreduce the surface parallax that causes shadowing in a mask formed onthe EUV mask blank 200. One of the limitation with the absorber layer,formed of chromium, tantalum or nitrides thereof having the thickness211 greater than 80 nm, is that the angle of incidence of the EUV lightcan cause shadowing which limits that pattern size that can achieved inan integrated circuit produced by a mask using the EUV mask blank, whichlimits the size of integrated circuit devices that can be fabricated.

It has been discovered that the selection of the material of the primaryabsorber layer 212 and the secondary absorber layer 214 is veryimportant for reflectivity loss due to path difference induced phaseshift. By way of an example, the embodiment can have the bi-layerabsorber 210 having a 30 nm thickness 211 made-up of the primaryabsorber layer 212 being a 27.7 nm layer of silver (Ag) and thesecondary absorber layer 214 being a 2.3 nm layer of nickel (Ni). Thisembodiment can provide a reflectivity percentage of only 0.58%.

An anti-reflective coating (ARC) 216 is deposited on the bi-layerabsorber 210. The ARC 216 can be of a material such as tantalumoxynitride or tantalum boron oxide.

A backside chucking layer 218 is formed on the back-side surface of theultra-low expansion substrate 202, opposite the planarization layer 204,for mounting the substrate on or with an electrostatic chuck (notshown).

Referring now to FIG. 3, therein is shown an orthogonal view of an EUVmask 300. The EUV mask 300 can be a rectangular shape and can have apattern 302 on the top surface thereof The pattern 302 can be etchedinto the ARC 216 and the bi-layer absorber 210 of FIG. 2 exposing thecapping layer 208 for representing the geometry associated with a stepin the manufacturing of an integrated circuit, not shown. The backsidechucking layer 218 can be applied on the backside of the EUV mask 300opposite the pattern 302.

Referring now to FIG. 4, therein is shown a flow chart of a method 400for making the EUV mask blank 200 with ultra-low defects. The ultra-lowdefects are substantially zero defects. The method 400 includes theultra-low expansion substrate 202 of FIG. 2 being supplied at an inputbase step 402. The ultra-low expansion substrate 202 can be backsidecleaned in a substrate cleaning step 404, degassed and pre-cleaned in abackside prep step 406.

The backside chucking layer 218 of FIG. 2 is applied in a back-sidechucking step 408 and a front-side clean is performed in a front-sidecleaning step 410. The mask blank 104, after the front-side cleaningstep 410, can be input to the first vacuum chamber 110 for furtherprocessing. The steps of forming a capped Bragg reflector 412 are betterperformed in the EUV mask blank production system 100 of FIG. 1 whileunder continuous vacuum to avoid contamination from ambient conditions.

A degas and preclean step 414 and planarization step 416 is performed inthe first vacuum chamber 110. The planarization layer 204 of FIG. 2 canbe cured in a planarization layer cure step 418 and the deposition ofthe multi-layer stack 206 of FIG. 2 is performed in a depositing themulti-layer stack step 420 can be performed in the second vacuum chamber112. The capping layer 208 of FIG. 2 can be deposited in a depositing acapping layer step 422 within the second vacuum chamber 112 for formingthe second in-process substrate 136, such as the capped Bragg reflector.

After exiting the EUV mask blank production system 100, the secondin-process substrate 136 is subjected to a deep ultraviolet(DUV)/Actinic inspection, which is performed in a close inspection step424, the second in-process substrate 136 is optionally cleaned in asecond front-side cleaning step 426, and the absorber layer 210 of FIG.2 and anti-reflective coating 212 of FIG. 2 can be deposited in an EUVmask blank completion step 428 for forming the EUV mask blank 200 ofFIG. 2.

It has been discovered that the EUV mask blank production system 100 canproduce the EUV mask blank 200 consistently with substantially zerodefects. The Application of the planarization layer 204 in the firstvacuum chamber 110 and the curing of the planarization layer 204 in thesecond vacuum chamber 112 can improve the efficiency of the EUV maskblank production system 100 because the chambers do not require thermalramp time between the deposition of the planarization layer 204 and itscuring.

Referring now to FIG. 5, therein is shown a flow chart of an alternativemethod 500 for making the EUV mask blank 200 with ultra-low defects. Theultra-low defects are substantially zero defects. The alternative method500 begins with the ultra-low expansion substrate 202 of FIG. 2 beingsupplied in an input base step 502. The ultra-low expansion substrate202 can be cleaned in a back-side cleaning step 504 and front-side canbe cleaned in a front-side cleaning step 506.

The steps of forming a capped Bragg reflector 508 are better performedin the EUV mask blank production system 100 of FIG. 1 while undercontinuous vacuum to avoid contamination from ambient conditions.

The mask blank 104 is degassed and pre-cleaned in a vacuum cleaning step510 performed in the first vacuum chamber 110. The backside chuckinglayer 218 is deposited in a chucking deposit step 512 and planarizationoccurs in a planarization step 514. The planarization layer 204 of FIG.2 can be cured in a planarization curing step 516, which can beperformed in the second vacuum chamber 112. The deposition of themulti-layer stack 206 of FIG. 2 is performed in a depositing themulti-layer stack step 518 and the capping layer 208 of FIG. 2 can bedeposited in a depositing a cap deposition step 520 for forming thesecond in-process substrate 136.

While the DUV/Actinic inspection may be performed inside the EUV maskblank production system 100, it may occur also outside in a closeinspection step 522. The second in-process substrate 136 is optionallycleaned in a second cleaning step 524, and the absorber layer 210 ofFIG. 2 and anti-reflective coating 212 of FIG. 2 can be deposited in anEUV mask blank completion step 526.

Referring now to FIG. 6, therein is shown an optical train 600 for anEUV lithography system. The optical train 600 has an extreme ultravioletlight source 602, such as a plasma source, for creating the EUV lightand collecting it in a collector 604. The collector 604 can have aparabolic shape for focusing the EUV light on a field facet mirror 608.The collector 604 provides the light to the field facet mirror 608 whichis part of an illuminator system 606.

The surface of the field facet mirror 608 can have a concave contour inorder to further focus the EUV light on a pupil facet mirror 610. Theilluminator system 606 also includes a series of the pupil facet mirror610 for transferring and focusing the EUV light on a reticle 612 (whichis the fully processed version of the mask blank 104 of FIG. 1).

The reticle 612 can have a pattern that represents a processing layer ofan integrated circuit. The reticle 612 reflects the EUV, light includingthe pattern, through projection optics 614 and onto a semiconductorsubstrate 616. The projection optics 614 can reduce the area of thepattern provided by the reticle 612 and repeatedly expose the patternacross the surface of the semiconductor substrate 616.

It has been discovered that embodiments planarize and smooth the EUVmask blank 200 of FIG. 2 so as to remove all pits, defects, andparticles on the substrate surface so that the surface is atomicallyflat and smooth. The deposition of defect free material on the surfaceof the EUV mask blank 200 can be processed without inducing any processrelated defects to achieve a flat and smooth surface. The EUV mask blank200 of FIG. 2 is a critical component of the optical train 600. Theoptical train 600 can sequentially position the semiconductor substrate616 for exposure to the pattern from the reticle 612 with no manualintervention.

Referring now to FIG. 7, therein is shown a plot 701 of a reflectivitypercentage 702 as a function of a thickness of the primary absorberlayer 212 of FIG. 2. A y-axis of the plot 701 can be the reflectivitypercent 702 of the bi-layer absorber 210 of FIG. 2. An x-axis can be thedimension of a thickness 704 of the primary absorber layer 212 in a 30nm embodiment of the bi-layer absorber 210.

A sample reflectivity 706 can show the resultant trace of thereflectivity percent 702 based on increasing the thickness 704 of theprimary absorber layer 212. The sample reflectivity 706 can show thethickness 704 of the primary absorber layer 212 being silver (Ag) in anickel-silver embodiment of the bi-layer absorber 210. The order inwhich the two layers are deposited is very important for reflectivityloss due to path difference induced phase shift.

An embodiment provides the bi-layer absorber 210 having the primaryabsorber layer 212 as a silver (Ag) layer, deposited on the cappinglayer 208 of FIG. 2, and the secondary absorber layer 214 of FIG. 2 as anickel (Ni) layer for providing a 30 nm combined thickness 211 of FIG.2. The oscillations shown in the sample reflectivity 706 are due to thephase matching of the bi-layer absorber 210 with the capping layer 208and the multi-layer stack 206 of FIG. 2. The total thickness 211 of thebi-layer absorber 210 is 30 nm. As can be seen from the graph, thelowest level of the reflectivity percent 702 is provided by 27.7 nm ofsilver and 2.3 nm of nickel to form the bi-layer absorber 210.

The embodiment assumes that the capping layer 208 is a thin Rutheniumlayer of 2 nm in thickness. The behavior of the bi-layer absorber 210 isplotted on the capped multilayer. An aspect of the bi-layer absorber 210is creating a path difference induced phase shift which will result in adestructive interference leading to reduction of the reflectivitypercentage 702. This behavior depends on the real part of the refractiveindex of the metal layers. FIG. 7 shows an embodiment of the bi-layerabsorber 210 as a nickel-silver bi-layered absorber. The reflectivitypercentage 702 as a function of increasing the thickness 704 of silveris shown as the sample reflectivity 706. The total thickness 211 of theabsorber stack is kept constant at 30 nm. So as the silver thicknessincreases, the nickel thickness simultaneously decreases. It is shownthat at 2.3 nm Ni and 27.7 nm Ag thicknesses, the overall reflectivityis 0.58%, which is much lower than the reflectivity for a pure 30 nm Ni(1.9%) or pure 30 nm Ag (1.6%) layers. The oscillation in the samplereflectivity 706 is due to the phase matching and mismatching due topath difference induced phase shift.

As shown in Table 1, the bi-layer absorber 210 formed of nickel (Ni) onsilver (Ag) provides substantially less reflectivity percentage 702 thanother combinations.

TABLE 1 The lowest reflectivity for a 30 nm bi-layer absorber is modeledfor a few metal systems. Bilayer Absorber 2nd absorber 1st absorber(M2)-(M1) (M2) nm (M1) nm Reflectivity % Ni—Sn 2.5 27.5 1.775%  Ni—Pt 228 1.80% Zn—Pt 2 28 1.28% Ni—Ag 2.3 27.7 0.58% Sb—In 2.5 27.5 1.75%Te—In 2 28 1.29% Ni—In 2.3 27.7 1.71% Zn—Ni 3.5 26.5 1.30%

Table 1 is a compilation of the lowest value of the reflectivitypercentage 702 for a 30 nm bi-layer absorber 210. The order in whichthese bi layers are deposited is very important for controlling thephase mismatching in the system. These embodiments of the bi-layerabsorber 210 can be deposited by PVD, CVD, ALD, RF, and DC magnetronsputtering techniques. Most of these metals form a very thin layer ofnative oxide, which affects the absorption and phase shift behavior verylittle at 13.5 nm.

TABLE 2 The smallest thickness required to get 0.8% reflectivity for abi-layer absorber. Total Absorber 2nd Absorber 1st Absorber thickness(M2) nm (M1) nm (nm) 3.9 Cu 28.6 Ni 32.5 3.2 Ni 23.3 Ag 26.5 3.6 Cu 28.9Sn 32.5 3.3 Sn 23.5 Ag 26.8 3.1 Cu 22.5 Ag 25.6 4.7 Cr 22.5 Ag 27.2 4.3Ta 22.4 Ag 26.7 6.1 Bi₂Te₃ 26.3 Sb₂Te₃ 32.4

The smallest of the thickness 704 required for the bi-layer absorber 210to get 0.8% reflectivity percentage 702 is tabulated in Table 2. Theselection criteria for these materials are based on the ability to beetched selectivity and the smallest thickness required to achieve 0.8%reflectivity percentage 702. The atomic scattering factors of thesematerials can have higher real and imaginary characteristics than otherelements in the periodic table. The higher imaginary characteristicaccounts for the absorption and the real part corresponds to the abilityto modulate the phase of the incident light. The phase modulation alsodepends on the thickness 704 of the absorber, since it's related to thepath difference induced phase shift.

The resulting method, process, apparatus, device, product, and/or systemis straightforward, cost-effective, uncomplicated, highly versatile,accurate, sensitive, and effective, and can be implemented by adaptingknown components for ready, efficient, and economical manufacturing,application, and utilization.

Another important aspect of the present invention is that it valuablysupports and services the historical trend of reducing costs,simplifying systems, and increasing performance.

These and other valuable aspects of the present invention consequentlyfurther the state of the technology to at least the next level.

While the invention has been described in conjunction with a specificbest mode, it is to be understood that many alternatives, modifications,and variations will be apparent to those skilled in the art in light ofthe aforegoing description. Accordingly, it is intended to embrace allsuch alternatives, modifications, and variations that fall within thescope of the included claims. All matters hithertofore set forth hereinor shown in the accompanying drawings are to be interpreted in anillustrative and non-limiting sense.

What is claimed is:
 1. An extreme ultraviolet (EUV) mask blankproduction system comprising: a substrate handling vacuum chamber forcreating a vacuum; a substrate handling platform, in the vacuum, fortransporting an ultra-low expansion substrate loaded in the substratehandling vacuum chamber; and multiple sub-chambers, accessed by thesubstrate handling platform, for forming an EUV mask blank including: afirst sub-chamber for forming a multi-layer stack, above the ultra-lowexpansion substrate, for reflecting an extreme ultraviolet (EUV) light;and a second sub-chamber for forming a bi-layer absorber, formed abovethe multi-layer stack, for absorbing the EUV light at a wavelength of13.5 nm provides a reflectivity of less than 1.9%.
 2. The system asclaimed in claim 1 wherein the bi-layer absorber includes a primaryabsorber layer and a secondary absorber layer formed on the primaryabsorber layer wherein the bi-layer absorber has a thickness of 30 nm.3. The system as claimed in claim 1 wherein the EUV mask blank furthercomprising a capping layer, formed on the multi-layer stack and thebi-layer absorber formed on the capping layer, for protecting themulti-layer stack.
 4. The system as claimed in claim 1 wherein the EUVmask blank absorbs the EUV light at a wavelength of 13.5 nm includesminimizing a reflectivity percentage by depositing a thickness of aprimary absorber layer and a secondary absorber layer of the bi-layerabsorber deposited to a combined thickness of 30 nm.
 5. The system asclaimed in claim 1 further comprising: an initial substrate handlingsystem in the substrate handling vacuum chamber for loading theultra-low expansion substrate; and a degas subsystem in a first vacuumchamber around the initial substrate handling system.
 6. The system asclaimed in claim 1 wherein the bi-layer absorber includes a primaryabsorber layer of Tin (Sn), Platinum (Pt), Silver (Ag), Indium (In), orNickel (Ni) deposited by the second sub-chamber.
 7. The system asclaimed in claim 1 wherein the bi-layer absorber includes a secondaryabsorber layer of Nickel (Ni), Zinc (Zn), Antimony (Sb), Chromium (Cr),Copper (Cu), Tantalum (Ta), or Tellurium (Te) deposited, on a primaryabsorber layer, by the second sub-chamber.
 8. The system as claimed inclaim 1 wherein the bi-layer absorber includes a primary absorber layerof Silver (Ag) and a secondary absorber layer of Nickel (Ni) depositedto a combined thickness of 30 nm.
 9. The system as claimed in claim 1wherein the bi-layer absorber includes a primary absorber layer ofPlatinum (Pt) and a secondary absorber layer of Zinc (Zn) deposited to acombined thickness of 30 nm.
 10. The system as claimed in claim 1wherein the bi-layer absorber includes a primary absorber layer ofIndium (In) and a secondary absorber layer of Tellurium (Te) depositedto a combined thickness of 30 nm.
 11. An extreme ultraviolet (EUV) maskblank system comprising: an ultra-low expansion substrate includessurface imperfections; a planarization layer on the ultra-low expansionsubstrate for encapsulating the surface imperfections; a multi-layerstack over the planarization layer; and a bi-layer absorber over themulti-layer stack includes determining a percent of reflectivity bycontrolling a thickness of a primary absorber layer and a secondaryabsorber layer of the bi-layer absorber deposited to a combinedthickness of 30 nm provides a reflectivity of less than 1.9%.
 12. Thesystem as claimed in claim 11 further comprising a capping layer, formedon the multi-layer stack and the bi-layer absorber formed on the cappinglayer, for protecting the multi-layer stack.
 13. The system as claimedin claim 11 wherein the thickness of the primary absorber layer includesthe range of 26.5 nm to 28 nm.
 14. The system as claimed in claim 11wherein the thickness of the secondary absorber layer includes the rangeof 2 nm to 3.5 nm.
 15. The system as claimed in claim 11 furthercomprising an additional multi-layer stack formed directly on theplanarization layer, wherein the additional multi-layer stack includesup to 60 of the multi-layer stack formed in a vertical stack.
 16. Thesystem as claimed in claim 11 wherein the bi-layer absorber includes theprimary absorber layer of Tin (Sn), Platinum (Pt), Silver (Ag), Indium(In), or Nickel (Ni).
 17. The system as claimed in claim 11 wherein thebi-layer absorber includes the secondary absorber layer of Nickel (Ni),Zinc (Zn), Antimony (Sb), Chromium (Cr), Copper (Cu), Tantalum (Ta), orTellurium (Te).
 18. The system as claimed in claim 11 wherein thebi-layer absorber includes the primary absorber layer of Silver (Si) andthe secondary absorber layer of Nickel (Ni) deposited to the combinedthickness of 30 nm.
 19. The system as claimed in claim 11 wherein thebi-layer absorber includes the primary absorber layer of Platinum (Pt)and the secondary absorber layer of Zinc (Zn) deposited to the combinedthickness of 30 nm.
 20. The system as claimed in claim 11 wherein thebi-layer absorber includes the primary absorber layer of Indium (In) andthe secondary absorber layer of Tellurium (Te) deposited to the combinedthickness of 30 nm.